1. Field of the Invention
The invention relates to a method of monitoring the operaton of a friction false-twisting unit for texturing thread.
2. Description of the Prior Art
Various thread monitoring and thread cutting devices are known which respond to irregularities in the thread, such as different stresses, broken thread, etc. One example is described in German Application DE-OS No. 30 05 746. These monitoring devices, however, are not capable of indicating irregularities such as variations in speed of rotation caused by defects in the drive elements, such as worn or jammed bearings or a damaged drive belt. The friction units continue to convey thread, which is found to be defective only during subsequent processing.
Friction false-twisting units typically include three driven shafts, each carrying friction disks, and the shafts are placed to that the disks are all interleaved. The shafts are driven by two toothed belts or by similar drive means and these present particular difficulties. The life of these drive belts, as is known, is not very long and differs greatly from one belt to the next. If only one belt tears in these units, the two other shafts are not affected and the thread continues to travel. Since the third shaft is not rotating, defective thread is produced. The defect itself is noted only by attentive personnel or during subsequent processing.
Similarly, a bearing may become worn or jammed. The two bearings which are still intact continue to travel with unreduced speed of rotation while the third shows irregularities. In this case also, defective thread may be detected only at a later time.